www.google.eshttp://www.google.es/patents/US3422068?utm_source=gb-gplus-sharePatente US3422068 - Method of producing an ortho-directed phenolic resin by condensing phenol and hcho in the presence of a bivalent metal ion and then adding resorcinol,and the resultant product

United States Patent 3,422,068 METHOD OF PRODUCING AN ORTHO-DIRECTED PHENOLIC RESIN BY CONDENSING PHENOL AND HCHO IN THE PRESENCE OF A BIVALENT METAL ION AND THEN ADDING RESORCINOL, AND THE RESULTANT PRODUCT Roland E. Kreibich, Harlan G. Freeman, and Gene F. Baxter, Seattle, Wash., and Karl F. Kumli, Chico, Califl, assignors to Weyerhaeuser Company, Tacoma, Wash., a corporation of Washington No Drawing. Filed Feb. 25, 1966, Ser. No. 528,772 US. Cl. 260--52 7 Claims Int. Cl. C08g /10 ABSTRACT OF THE DISCLOSURE A process of manufacturing ortho-directed, phenolformaldehyde resins modified with resorcinol or other polyhydroxy aromatic compounds which have a relatively long shelf life and relatively short cure time by condensing phenol and formaldehyde to near completion under reflux conditions in the presence of bivalent metal ion catalyst, adding resorcinol or other polyhydroxy aromatic compounds to the reaction product of phenol and formaldehyde, and continuing heating of the mixture under reflux condition until the reaction is substantially complete. The molecular ratio of phenol to formaldehyde is between 0.55 to 1.2 moles formaldehyde per mole of phenol and the molecular ratio of resorcinol or other polyhydroxy aromatic compound to phenol ranges between 0.2 to 0.8 m'oles.

The final copolymer has a predominantly linear backbone of ortho-directed phenol-formaldehyde modified by resorcinol or other polyhydroxy aromatic compound forming methylene bridges cross-linking molecules to adjacent molecules to provide an infusible final product.

This invention relates to the production of a resin produced by reacting an aldehyde with a phenol in the presence of a particular catalyst and further reacting the combined phenol-aldehyde mass with polyhydroxy aromatics. More specifially, this invention relates to the production of a phenol-formaldehyde resorcinol resin in the presence of an ortho-directing catalyst.

In the manufacture of laminated wood products, it is the usual practice to spread an adhesive between at least two wooden laminates and then press them together at either ambient or elevated temperatures.

In recent years the forest product industry has developed highly sophisticated machinery for rapidly moving laminates together with adhesive therebetween for bonding. However, in order to effectively bond the laminates together, it is required that they remain in the press a predetermined period of time. Therefore, the rate of production is dependent on the length of time the laminates need to be in the press.

The adhesives used in these systems are usually formed from a phenol formaldehyde resin having conventional additives mixed therewith. The phenol and formaldehyde are combined by cooking a predetermined amount of each component together in the presence of an alkaline catalyst. The end product is a resin polymer that Will cure a hard infusible state when subjected to heat. While these resins form a good bond between a pair of laminates, they generally require long press times at high temperatures.

In order to reduce the long press time when using a phenol-formaldehyde resin, it has been proposed to modify this resin with a resorcinol-aldehyde reaction product. However, in practice it has been found that press times are not appreciably reduced by this type of resin.

3,422,068 Patented Jan. 14, 1969 Also, it has been proposed to add resorcinol to the combined phenol-formaldehyde polymer to shorten press time for complete cure. However, this expedient seriously reduces the pot life of the resin product which requires immediate use of the resin; but, most production lines require storage of the resin to ensure an adequate supply. Thus, this type of resin has been proven to be unsatisfactory.

The object of this invention is to provide a method of producing a phenol aldehyde resin modified with a polyhydroxy aromatic compound that has a relatively long shelf life and a relatively short cure time at ambient or moderately elevated temperatures.

Another object of this invention is to provide a resin product by reacting an aldehyde with phenol in the presence of an ortho-directing catalyst and further modified with resorcinol to provide the resin with a relatively long shelf life and a relatively short cure time.

In the practice of the present invention, phenol and formaldehyde are mixed together in a cooking vessel of any desired size in the presence of an ortho-directing catalyst. A catalyst suitable for use with the present invention is a bivalent metal ion such as calcium, magnesium, zinc, strontium, cadmium, or barium. In use, the catalysts are usually bivalent metal salts of weak organic acids that are soluble in phenol-formaldehyde mixture. Typical are the acetate, citrate, glycolate, and tartrate salts.

During the initial cooking stage of formulating the resin, a particular amount of formaldehyde is used with the phenol. It has been found that a molecular ratio of from 0.55 to 1.2 moles of formaldehyde per mole of phenol is suitable. The pH of this reaction mass will be about 6. The phenol formaldehyde mass is cooked at refiux temperature in the presence of the bivalent metal catalyst until the reaction is near completion. By the term near completion it is meant that the viscosity of the reaction mass is about centipoise at 25 C. with a solid content of up to 65%. The formaldehyde will attach predominately at the ortho position to provide the following typical polymer:

wherein n is preferably a number greater than 1 and will depend on the molar ratio of the phenol and formaldehyde.

The temperature of the phenol formaldehyde reaction mass is now slightly reduced below reflux temperature and resorcinol is added. The amount of resorcinol added may range from between 0.2 to 0.8 mole of resorcinol per mole of phenol. By adding the resorcinol to the reaction mass, the temperature thereof will be further reduced. This initial reduction of temperature will allow the intermixing of the resorcinol throughout the phenol formaldehyde reaction mass before substantial reaction takes place. The temperature of the phenol formaldehyde resorcinol mass is then raised back up to reflux temperature of approximately 96 to 98 C. After the phenol resorcinol formaldehyde mass has been reheated, an alkali metal hydroxide, water and an alcohol may be added. The function of the alcohol is to prevent phase separation of the resin during storage. The function of the alkali metal hydroxide is to stabilize, catalyze and wet and may be used in an amount ranging up to about 11% by weight.

The resorcinol phenol formaldehyde mass is then cooked until the viscosity is between 620 and 1300 centipoise. The time necessary to complete the cook is about H CHzOH 3 4 5 hrs. In order to increase the reaction rate between the vent separation of the hardener dispersion and imparts phenol formaldehyde and resorcinol, the whole mass may thixotropy to the hardener and to the mixed glue. The be placed under pressure. This expedient will necessarily hydroxyethyl cellulose and the wetting agent aid in disincrease the reflux temperature and a faster reaction'rate persing the solid ingredient of the hardener and prevent separation. The hydroxyethyl cellulose also serves as a protective colloid for the dispersion.

will occur. After the mass has reacted to the degree as set forth, the reaction mass is then cooled and Shipped to the mill to be further processed and used. The resin mass The above hardener is mixed with the resin mass at to be shipped to the mill will have a storage life of about a ratio of from 1 to 5 parts of resin per 1 part of hard- 30 days and will contain at least 50% solids. The resin ener. After the hardener has been thoroughly mixed with product will have the following typical formula; the resin, the resin begins to react and now has a very short pot life. Accordingly, it is desirable that the resin and hardener be continuously mixed together and con- OH OH 0H OH I H r I I DH l tinuously applied to the wood to be bonded together. I CH 0II The continuous mixing and metering may be done by any 011 H H commercial mixer capable of mixing two liquids together at a predetermined ratio.

wherein n is preferably a number greater than 1 and will The adhesivfi that is pp to the Wood to be bonded depend on the molar ratio of the phenol and formaldetogether will have a Viscosity of Preffirably betwefin 600 hyde, and 8000 centipoise to provide the requisite spreadability When it is desired to formulate a thermosetting adheproperties thereof. The molecular ratio of the resorcinol sive from the above resin, it is required that a hardener be to phenol will be between .2 to .8 mole of resorcinol per mixed therewith. It has been found in practice that commole of phenol with the molecular ratio of formaldehyde mercial powdered hardeners consisting of a mixture of to total phenolics of 0.70 to 2.0. The final adhesive prodparaformaldehyde and fillers cannot be suitably employed uct will have the following typical formula:

0H OH OH OH I r on CH, --CH on.- c (1- l g, L g} CH.- OH

11 ('JH; l

with the resin of this invention. Such hardeners have the 5 wherein n is preferably a number greater than 1 and will possibility of caking or lumping under humid conditions depend on the molar ratio of the phenol and formaldeand require long and complicated mixing requirements to hyde. It is apparent from this formula that methylene blend the lightweight powders with the liquid resin. Acbridges have been formed, crosslinking the molecule to cordingly, a novel type liquid hardener was formulated. adjacent molecules, to provide the infusible final product.

The process for formulating the hardner is to mix 10 to 40 As has been pointed out above, the resin will be at least 50 parts of water, up to parts of an alcohol and 10 to 50% solids by weight. However, for some particular types 70 parts of formaldehyde in a vessel and stir continuous of bonding procedures, it is not necessary to provide such ly for a sufficient length of time to fully interrnix these ina high solids content of the resin. Accordingly, the resin gradients, Th ft a d bl d of b t e 15 d may be diluted by adding water thereto in a particular parts filler and up to 2 parts hydroxyethyl cellulose is manner. The mere expedient of adding additional water mixed in with the water, alcohol and formaldehyde. This Will not result in a Satisfactory resinmixture is blended until the dry ingredients are thorough- Accordingly, when a resin is formulated having less ly intermixed therein. Then up to 5 parts of pyrogenic solids therein, it is necessary to add water with the re silica is added to the mixture and thoroughly mixed until sorcinol when it is added to the reaction mass of the a smooth paste is formed. Then up to 13 parts of formphenol and formaldehyde. The amount of water will be aldehyde is added to the mass along with up to 2 parts dictated in accordance with the amount of solids that of a wetting agent and the whole mass is then thoroughly are required in the final product. Ordinarily, sutficient mixed. After the mass is thoroughly mixed, it is strained Water can be added to Pmdllce resin having a final Solids into a shipping container and stored. The mixture is thixo- Content of 35% based on the Weight of the final resin. tropic and does not readily Settle out Aft long Periods This resin can then be mixed with the hardener and formuof Standing, a shallow, clear liquid layer may form on lated asset forth above for the final resin adhesive prodtop but can be il mixed The Product is a thick, uct. ThlS resin will have the same molecular ratio and approximately the same viscosity as the resin noted above only with fewer solids based on the weight percent.

The above resin has found wide acceptance in the laminating industry because of the durability and cold setting nature of the resorcinol phenol formaldehyde resins. Particular acceptance has been found when laminating exterior beams. In other applications, the resorcinol phenol formaldehyde resins are advantageous because of milky liquid.

As can be seen, the hardener consists of a liquid mixture of filler and aldehyde. Suitable fillers can be various clays, silica flour prepared from crystalline or amorphous silica, nutshell flours, chalk fiour, powdered asbestos and bark and wood flours. Of these, aluminum silicate clay, walnut shell flour, and crystalline silica flour have been found to have the most deslrabl? Propel-hcombmanolls their cold setting and rapid heat curing features and the of these finfirs may be used Smtablyof the aldehydes: 1t durable nature of the resin after cure. The chief limitahas been found that aqueous Paraformaldehyde disper' tion, however, of these resins is their high cost due to Sims, Various formalin Solutions, g y and fuffuralalde' the expense in obtaining resorcinol. Accordingly, the wood y 310116 in Combinations are Suitable- However, y 7 laminating companies and their suppliers have put forth aldehyde with enough activity to harden the phenol rea great deal of effort to try to replace the resorcinol sorcinol polymer at room or intermediate temperature portion of the resins.

is suitable. The other ingredients serve as modifiers and In accordance with another feature of this invention, stabilizers. Alcohol stabilizes formalin solutions against it has been found that a low cost polyhydric aromatic precipitation and gelation. The pyrogenic silica helps precompound can be substituted for the resorcinol in the above resins. Tests show that such a substitution in conventional resin formulations results in a resin that is clearly unsatisfactory for most resin uses. These polyhydric aromatics are polyhydric, polynuclear aromatics and may also include one or more of the di-hydroxy benzenes. The above materials may be prepared by reacting monochlorophenols with alkali metal hydroxides in accordance with Belgian Patent No. 663,903 filed May 13, 1965, and issued to Dow Chemical Company of Midland, Mich. While the compositions per se above noted form no part of the present invention, it has been found that these materials may be substituted for the resorcinol content in the resin formulations as herein defined. Accordingly, for a complete disclosure of the process for formulating the above compositions and the description of the compositions per se, reference is made to the above-noted Belgian patent.

In order to illustrate the merits of the present inven-.

tions, reference is made to the following examples:

Example I A resin was formulated by mixing together 45.48 parts by weight of 90% phenol (90% phenol and water), 11.11 parts by weight 91% paraformaldehyde, 4.37 parts by weight water, and 0.44 part by weight calcium acetate in a cooking vessel which was heated to reflux temperature of 106 C. uniformly in 60 min. The temperature of the materials in the cooking vessel was held at the reflux temperature for 135 min. and then was slightly cooled. It was found that the phenol and formaldehyde had combined and had a viscosity of 125 centipoise at 25 C., a pH of 6, and an oven solids content of 60.1 parts by weight. Thereafter, 19.19 parts by weight resorcinol was added to the phenol formaldehyde reaction mass and heated back to reflux in min. Then 6.55 parts by weight water, 9.59 parts by weight ethanol, and 3.27 parts by weight of a 50% solution of sodium hydroxide were added to the reaction vessel. The entire mass was then cooked at reflux temperature between 96 and 98 C. until the reaction mass reached a viscosity of between 880 and 1070 centipoise measured at 25 C. The mass was then cooled to room temperature and stored.

Example II A second resin formulation was made by placing in 6 Example III A liquid hardener was formulated by placing in a vessel 32.40 parts by weight water, 3 parts by weight methanol, and 30.00 parts by weight of 46.5 formalin. This mixture of materials was stirred continuously. A dry blend of 25 parts by weight ASP-400 clay filler and .12 hydroxyethyl cellulose was prepared. This dry blend was added to the vessel and stirred in while 4.40 parts by weight Cab-O-Sil M5, pyrogenic silica, was added. A smooth paste was achieved. Then 5 parts by weight 46.5% formalin was added along with .10 parts by weight Advawet 43, wetting agent. This mixture of materials was mixed thoroughly and then strained into a shipping container through a 30-mesh screen and stored. The viscosity of this material measured on a Brookfield viscometer with a No. 4 spindle was as follows: at 6 r.p.m., viscosity 10,000 centipoise; at 12 r.p.m., 6000 centipoise; at 30 r.p.m., 2940 centipoise.

Example IV The resin of Example I and liquid hardener of Example III were mixed together at a ratio of 5 parts of resin to 2 parts of hardener in a continuous manner and then applied to Douglas fir boards and laminated into beams. Tests were performed on the laminated beams using CS25363 procedures with the following results:

TABLE I Test results Clamp time hours at 22 C. P.s.i. Percent Percent wood failure delaminatiou Example V A series of resins was made in accordance with the formulation as set out in Example I but varying the amount of resorcinol used with the amounts of the other constituents being held constant. Each of the resins was admixed with the liquid hardener of Example III at a ratio of 5 parts resin to 2 parts liquid hardener. Tests a cooking vessel 28.89 parts by weight 90% phenol (90% 45 on this adhesive mix were as'follows:

phenol and 10% water), 7.57 parts by weight 91% paraformaldehyde, 3.31 parts by weight water, and 0.28 part by weight calcium acetate. The ingredients were heated to reflux at 106 C. uniformly in min. The mass was held at the reflux temperature for an additional 135 min. and then slightly cooled. Then 12.39 parts by weight resorcinol was added to the phenol formaldehyde reaction mass and heated back to reflux in 15 min. Then 16.89 parts by weight water and 2.12 parts by weight of a 50% solution of sodium hydroxide was added. This mass was then cooked at reflux to a viscosity of 3620 centipoise measured at 25 C. Then 22.35 parts by weight water and 6.20 parts by weight ethylene glycol was added and cooked until the mass had a viscosity of 627 centipoise measured at 25 C. The resin was then cooled to room temperature and stored.

Example VI Example VII The resin of Example I was formulated but modified by substituting a mixture of polyhdric aromatic com pounds for the resorcinol content on a weight basis. An 5. A process for the manufacture of a resin composiadhesive was formulated from this resin by adding thereto tion, comprising the steps of: a liquid hardener in accordance with Example III at a (l) reacting formaldehyde and phenol to near compleratio of parts resin to 2 parts hardener. The adhesive tion under reflux conditions in the presence of a was placed on boards which were laminated together. A bivalent metal ion catalyst, the molecular ratio of conventional phenol formaldehyde resorcinol resin was 5 formaldehyde to phenol being between 0.55 to 1.2 again formulated except a mixture of polyhdric aromatic moles formaldehyde per mole of phenol, materials was substituted for the resorcinol content. The (2) adding a mixture of polyhydroxy aromatics includconventional resin was formulated in the conventional ing dihydric-phenols, polyhydroxy-polyphenol ethers manner using a sodium hydroxide catalyst. Block shear 10 and polyhydroxy-polyphenyls formed by the reaction tests for the two resins were then performed using a 7 of at least three moles of an alkali metal hydroxide hour clamp time at 22 C. and 150 p.s.i. with the result with a chlorophenate at a temperature of from 200 that the resin of Example I, but modified by employing a C. to about 350 C., while maintaining the reaction mixture of polyhydric aromatic compounds. for the reproduct of formaldehyde and phenol at an elevated sorcinol content, had a shear strength of 880 p.s.i. at 7 l5 temperature, and hours clamp time while the conventional catalyzed resin (3) heating the reaction mass under reflux conditions hadashear strength of 260 p.s.i. until the viscosity is between 620 and 3000 centi- From the above examples and tables, it is clear that P the resin and adhesive of this invention exhibit bonding 6. A resin having predominantly the structure:

OH OH OH OH H r H] OH 11: CH. 0112-- -h- 3-- g L CH2- OH OH properties and shelf life in quantities far superior to those wherein the molecular ratio of resorcinal to phenol ranges of a conventional phenol formaldehyde resorcinol resin. from 0.2 to 0.8 mole resorcinol per mole phenol, the mo- While specific details of preferred embodiments have lecular ratio of formaldehyde to total phenolics ranges been set forth above, it will be apparent that many. from 0.70 to 2.0 moles formaldehyde per mole total changes and modifications may be made therein without phenolics, n is greater than 1, and the Viscosity ranges departing from the spirit of the invention. It will, theretwee 600 and 8000 centipoises.

fore, be understood that what has been described herein The P according to Claim 1 wherein formis intended to be illustrative only, and is not intended to aldehyde and phenol are reacted together to a viscosity limit the scope of the invention. of about 125 centipoises at 25 C.